When a clinician or other person in the medical field wishes to insert a needle into the vein of a patient for subsequent application of medication, or for other reasons, it is important that that person know when vein entry has been made. That is, the needle is inserted through the skin of the patient and the point of the needle proceeds inwardly until one side wall of the vein has been punctured. It is at this point that the technician or other person making the vein entry understand that the vein entry has actually been made so that the injection or other anticipated procedure can then follow.
Because the introduction of the assembly into the vein is normally accomplished by the use of a rigid metallic needle, it is impossible to detect the presence of blood in the needle and needle hub and, likewise, the presence of the needle tip in the vein. For example, introducer needles are normally equipped with a hub at the proximal end thereof, and some devices have equipped the hub portion of the needle with a transparent flash chamber into which the blood may flow in order to indicate to the user that the needle point is properly placed. However, in order to induce blood flow from the needle point to the flash chamber venting of air therefrom is required, and the flow of blood from the flash chamber was controlled by a plug that was inserted into the chamber after the blood had actually appeared therein. As a consequence, if the plug was not placed at the proper time, blood would flow from the chamber through the air vent and leak over the person using the instrument.
One approach to this undesirable effect of having the user of a device become contaminated with blood flowing during the time that they were attempting to indicate whether there was vein entry, arrangements have been made to provide a blood-detecting chamber at the proximal end of the device with the chamber being provided with a convenient means for venting air from the needle cannula. As the blood flows from the vein toward the proximal end of the device, the vent will expel air and allow for the blood detecting chamber to be filled with blood so that the user knows that vein entry has been made, but still provide a venting action which would not allow the blood to flow through the vent.
Many arrangements have been made of configurations of vents in order to prevent actual blood flow through the vents, while still providing the proper venting of the air from the chamber or cannula of the needle so that blood will actually be induced to flow from the vein of the patient to the proximal end of the device where the blood detecting chamber is located. One such device is described and claimed in U.S. Pat. No. 3,859,998 which utilizes a breather slit in the "flashback" chamber at the proximal end of the device. The slit allows for the air to pass so the blood will flow to the flashback chamber which is a transparent walled chamber so that blood can be viewed therein. The slit is of a dimension which prevents blood from flowing from the flashback chamber onto the user of the device.
However, such slits are not always completely satisfactory and blood leakage does take place. Aside from this, there is an amount of time taken from the time of vein entry until the time that the blood flows to the flashback chamber. During this procedure, the user may have inserted the point at the distal end of the cannula inwardly too far and passed entirely through the vein to the opposite wall thereof so that there is not, in fact, vein entry for the subsequent application of the use of the instrument, as desired.
Other arrangements for enhancing the use of a flashback chamber include the invention described and claimed in European Patent Publication No. 0139872 which shows a flashback chamber with a magnifier 13. This has the effect of increasing the visual appearance of blood in a transparent flashback chamber, so that the user may more quickly realize that vein entry has been made.
A further structure designed to indicate that vein entry has been made, utilizing a flashbacktype chamber for visual observation of the presence of the flow of blood is taught and claimed in U.S. Pat. No. 4,365,630, which teaches a transparent maze-type arrangement for indicating to the user the presence of blood and the fact that vein entry has been realized. While this reduces the time from vein entry until a visual indication thereof, there is still a time interval which may cause difficulties, as discussed above.
With this invention, by contrast, a new arrangement is provided in which the user realizes instantaneously when vein entry has been made. That is, no blood flow is required to a flashback chamber and, indeed, no flashback chamber is present. The invention here utilizes a fiber optic which extends through an intravenous needle, for example. The front end of the fiber optic is flush with the distal end of the introducer needle. The front end, in turn, of the fiber optic is ground so that it is indeed flush with the needle point as it is inserted through the wall of the vein of a patient.
The fiber optic is an elongated device with an outer diameter of a size which will fit through the internal diameter of the lumen of the needle involved. The fiber optic extends to the proximal end of the needle to a one-piece solid magnifying assembly which projects the indication passing visually through the fiber optic from the polished front or distal end of the fiber optic to indicate instantaneously vein entry.
That is, a magnifying arrangement provides optical illumination of the actual vein entry so that no blood is required to flow through the introducer needle to the rear end thereof prior to such time that vein entry is realized. The user will know simply by looking at the magnifying surface that the dark red color of venous blood is present at the distal end of the needle and the fiber optic.
In order for the observer to observe vein entry, there must be sufficient light at the distal end of the needle and fiber optic. This is realized in a number of ways. First, for situations where the skin is fairly thin and translucent (for example in neonates, babies and elderly) ordinary good ambient lighting is sufficient. In situations where the skin is thicker, darker or dark pigmented, it is necessary to have supplemental lighting. This is accomplished using any light source which externally illuminates the area where vein entry is to take place.
One particular device that works particularly well for this situation is the Landry Vein Light.TM., a product of Applied Biotech Products, Inc., Scott, LA 70583, which illuminates peripheral veins for intravenous therapy. A further approach is to concentrate supplemental lighting through the proximal end of the fiber optic with lenses molded into the plastic hub in accordance herewith.
With this arrangement, therefore, no venting is required. No blood flow is required. The arrangement is bloodless so there is no fear of contamination by the user of the blood of the patients involved. Moreover, because the fiber optic can be made of any dimension, it works for all gauges of needles, even such small gauge needles as 30 gauge. There is constant monitoring of the needle tip with, as indicated above, instant indication of vein entry and/or any other conditions present at the distal end of the needle, for that matter.
Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings and the appended claims.